Indiosides G–K: Steroidal Glycosides with Cytotoxic and Anti-inflammatory Activities from Solanum violaceum

Chiao-Ting Yen†, Chia-Lin Lee‡§, Fang-Rong Chang†, Tsong-Long Hwang, Hsin-Fu Yen, Chao-Jung Chen‡, Shu-Li Chen†, and Yang-Chang Wu*†‡§O

^† Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung 80708, Taiwan, Republic of China

^‡ School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung 40402, Taiwan, Republic of China

^§ Natural Medicinal Products Research Center, China Medical University Hospital, Taichung 40402, Taiwan, Republic of China

Graduate Institute of Natural Products, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan, Republic of China

Botanical Garden, National Museum of Natural Science, Taichung, 40453, Taiwan, Republic of China

Proteomics Core Laboratory, Department of Medical Research, China Medical University Hospital, Taichung, 40402, Taiwan, Republic of China

^O Center for Molecular Medicine, China Medical University Hospital, Taichung 40402, Taiwan, Republic of China

J. Nat. Prod., Article ASAP

DOI: 10.1021/np200877u

Publication Date (Web): March 13, 2012

Five new steroidal glycosides (1–5) and nine known compounds were isolated from Solanum violaceum. Indiosides G (1) and H (2) are spirostene saponins with an iso-type F ring, indioside I (3) is a spirostane saponin, and indiosides J (4) and K (5) are unusual furostanol saponins with a deformed F ring. These structures represent rare naturally occurring steroidal skeletons. The structures of the new compounds were elucidated using 1D and 2D spectroscopic techniques and acid hydrolysis. Compounds 2, 3, and 7–9 exhibited cytotoxic activity against six human cancer cell lines (HepG2, Hep3B, A549, Ca9-22, MDA-MB-231, and MCF-7) with IC₅₀ values of 1.83–8.04 μg/mL. Steroidal saponins 3, 8, and 9 showed inhibitory effects on superoxide anion generation with IC₅₀ values of 2.84 ± 0.18, 0.62 ± 0.03, and 1.62 ± 0.59 μg/mL, respectively. Saponins 8 and 9 also inhibited elastase release with IC₅₀ values of 111.05 ± 7.37 and 4.04 ± 0.51 μg/mL, respectively. Structure–activity relationship correlations of these compounds with respect to cytotoxic and anti-inflammatory effects are discussed.

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